Critical comments are made on the experimental results for zero field current density j/sub 0/ and work function obtained by J.W. Gibson et al. (ibid., vol.36, no.1, p.209-14, 1989) on top-layer scandate cathodes and on an emission model proposed for them. It is shown, for example, that the determination of j/sub 0/ gives rise to erroneous results.<>
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An image sensor and a 16×16 pixel test device consisting of a MOS transistor array overlaid with an a-Si:H photoconductive film are presented. The sensor operates by applying the potential induced on the surface of a a-Si:H film directly to the gates of the MOS transistors, and then reading out the modulated drain currents. Photosensitivity is 4-5.6 μA/(nJ/cm2) for incident lig...
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In order to design submicrometer Si MOSFETs properly, the specific contact resistivity ρc has to be controlled. The ρ c is known to be a function of both the barrier height and the Si surface doping concentration. An existing theory is used to generate ρc, emphasizing details in the practical regimes, with a careful choice of proper parameters such as t...
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Fluorine was implanted into the polysilicon gate and diffused into the gate oxide by annealing at 1000°C. Transconductance (g m) for the devices with high dosages of fluorine implantation decreased linearly in stress time, while gm for devices without fluorine and with low implantation dosages decreased by almost the square root of stress time. Device li...
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Electron emission characteristics for the cone and wedge generic field emitter structures are described. Effects of variations in emitter geometry on electron current, spectral and temporal dispersion of electron emission, and emitter heating are calculated analytically and by computer simulation. Several guidelines for emitter design are suggested
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Photodetection response measurements performed on normally off GaAs photo-MESFETs are discussed. Two modes were investigated: (i) the normal mode in which the photon energy is greater than the bandgap and the light intensity is sufficient to bias the device above turn-on-threshold, and (ii) the subthreshold mode with subband-gap photon energy illumination. In the second mode, the transistor operat...
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The effect of electron energy on the two-dimensional electron gas (2D EG) transport properties of high-electron-mobility transistor (HEMT) structures at low temperatures is measured. The structures were grown by molecular beam epitaxy (MBE) with a 2D EG approximately 850 Å below the surface. The HEMTs were fabricated into Hall bars, and damage was assessed by changes in the 2D EG concentrati...
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A plasma-deposited semi-insulating silicon nitride (SinSiN) developed as a resistive sea passivation is discussed. Following a brief review of its properties, its use as a resistive sea is reviewed. It is shown that SinSiN can be used to improve the breakdown voltage of a high-voltage device by some 20 to 40 V by screening all surface charges. It is also shown that SinSiN provides device immunity ...
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Hot-carrier-induced degradation surface-channel (p+ polysilicon gate) and buried-channel (n+ polysilicon gate) pMOSFETs is discussed. In the shallow gate bias region, a hot-carrier degradation mode by drain avalanche hot hole injection was found for the surface-channel pMOSFETs. Trapped holes and interface state generation, which were not observed in the buried-channel pMOSFE...
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An analysis of the current dependence is performed using a partitioned transistor equivalent circuit that includes the distributed effects of the emitter contact. It is shown that the emitter resistance increases with current if emitter current crowding is important. The current dependence of the emitter resistance is extracted as a function of the specific contact resistance and the base and emit...
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A saturated instantaneous bandwidth (FWHM) of at least 10% in a Ka-band gyrotron traveling-wave tube (gyro-TWT) with uniform interaction waveguide and magnetic field was obtained. A relatively low α(≡ν⊥/ν||) beam has resulted in stable saturated operation and broad bandwidth. This, together with the overall performance of the tube (18.4-kW maxi...
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Two-dimensional imaging of a minority-carrier packet is reported. Displacement of the minority carrier according to the clock pulse can be visualized. Utilizing the sampling gate technology, it is possible to analyze the timing operation of digital circuits. The advantage is that it is accessible to any point on the chip, requiring no direct contact probing or vacuum system. There is no interactio...
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The theory developed by M. Chodorow and E.L. Chu (Stanford Univ. Tech. Rep. TR249, 1954) is expanded to include the problem of a contrawound helix interposed between two dielectric regions, symmetrically oriented inside a conducting cylinder. The single helix oriented in an identical fashion is simultaneously analyzed. Numerical results are presented in the form of dispersion diagrams over a wide ...
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An algorithm for obtaining analytical expressions for the normalized secondary emission ratio δ/δmax as a function of the normalized impact voltage is presented. These expressions are well suited for implementation on personal or mainframe computers with a very high accuracy over the whole range of the normalized impact voltage
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A two-dimensional physical model which includes the effects of deep levels in semi-insulating GaAs is described and applied to an investigation of the effects of trapping phenomena in the substrate of a GaAs MESFET. The model is used to investigate some of the anomalous features of the operation of these devices which have in the past been attributed to traps near the channel-substrate interface. ...
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An analytical model of the energy distribution of hot electrons in semiconductors is presented. It is derived under the simplifying assumptions of a single nonparabolic conduction band, small space derivative of the external electric field, and emission of optical phonons as the dominant energy loss mechanism. The model, indicating that band nonparabolicity makes the electron energy distribution d...
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A pseudomorphic HEMT employing a thick Inx/2Ga1-x/2As buffer layer on a GaAs substrate substrate is proposed in order to use an InxGa1-xAs channel with a large InAs mole fraction. This buffer layer acts as a substrate with intermediate lattice constant. Transmission electron microscopy observations revealed that good-quality crystal can be obtained using...
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The electrical properties of field oxide isolation structures are investigated from the device physics point of view. The importance of the potential barrier formation mechanism is clearly demonstrated through the derivation of an analytical formulation of the subthreshold current. The current independence on the isolation device length is clearly established. A large range of ideal field oxide ge...
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This scaling scheme is based on a charge retention model which successfully explains the observed charge loss phenomena of an advanced erasable programmable read-only memory (EPROM) cell with an oxide-nitride-oxide (ONO) film as the interpoly dielectric. It is shown that there are three distinct phases in EPROM charge retention characteristics. The main sources of charge loss are charge movement i...
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A clocked latch functioning as a simple comparator with InAlAs/InGaAs heterojunction bipolar transistors (HBTs) on an InP substrate is discussed. Typical comparator offset voltages of 2 mV, and as low as 0.2 mV, along with differential pair measurements indicate good Vbe matching of the HBTs in the circuit. A thermal hysteresis of approximately 1 mV was measured. These results ...
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Two different methods of calculating the small-signal gain of a traveling-wave tube (TWT) based on J.R. Pierce's standard theory (1950) and the theory of finite beam thickness of K. Ura and M. Terada (1962) are described. Three broadband TWTs were built and tested. The experimental results are compared with the theoretical values calculated by the two methods. The method based on the theory of Ura...
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The analysis indicates that a thinner gate oxide nMOSFET shows smaller degradation. Mechanisms for the smaller degradation were analyzed using a simple degraded MOSFET model. It was found that the number of the generated interface states is defined uniquely by the amount of peak substrate current, independently from the gate-oxide thickness. The major cause of the smaller degradation in the thinne...
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The dispersion characteristics of a helix-loaded traveling-wave tube (TWT) when a dielectric or plasma is introduced into the system are discussed. The dispersive properties of the dielectric-supported helix waveguide are examined for different geometric parameters of the helix waveguide. The dispersion relation of the helix mode is upshifted by ωp2 cos2 &phi...
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An analytic and numerical study of the feasibility of depressed collectors for gyrotrons for accelerator applications is discussed, and a specific design for a 10-GHz 30-MW gyroklystron is realized. The conclusion of the study is that depressed collectors are feasible for gyrotrons of interest for accelerator applications (i.e. P&les;100 MW, 10 GHz<f<35 GHz) and that their ...
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Aims & Scope

IEEE Transactions on Electron Devices publishes original and significant contributions relating to the theory, modeling, design, performance and reliability of electron and ion integrated circuit devices and interconnects.